Powerful gas turbine systems have a rotor unit which, depending on the output capacity, typically have lengths of approximately 10 m, along which a compressor unit, the combustion chamber and at least one turbine stage are arranged. In the case of so-called sequentially operated gas turbine systems, a second combustion chamber and a further, downstream turbine blade arrangement are additionally provided along the rotor unit. Rotor units of this kind, which are predominantly made in one piece, are completely surrounded by a stationary housing which for the purpose of stable mounting of the overall gas turbine system in relation to a base is supported by way of a plurality of supports. For an illustration of the mounting concept used hitherto for gas turbine systems, the reader is referred to FIGS. 2a and b, where FIG. 2a is a diagrammatic cross section through a gas turbine system, and FIG. 2b is a perspective overview of a gas turbine system and the supports required to mount it. Conventionally, for the purpose of mounting a substantially tubular gas turbine system 1 there serve support struts 13 which rise vertically above a base 22 and at one end are firmly connected to the base 22 and at the other bear against corresponding support contoured elements 4 on the housing 5. Typically, a plurality of support struts 13 that are spaced axially in relation to the gas turbine system 1 serve to provide a reliable mounting of the gas turbine system 1 in three dimensions in relation to a base 22 which takes up the entire force of the weight of the gas turbine. It can be seen from the perspective illustration in FIG. 2b that in each case a plurality of support struts 13 are provided to left and right of the engine axis A in order to support the gas turbine system 1. It is clear that vibrations in operation as a result of the large masses set in rotation by the rotor unit 6 are almost unavoidable and will become clearly evident in the form of structural resonance, in particular close to the rated operational speed of rotation of the gas turbine system, and depending on their intensity will at the least impair start-up of the gas turbine system and at worst will make it impossible. An additional factor is the fact that, because of longitudinal thermal expansion, a mounting of a gas turbine system must on the one hand provide slide faces for expansion in the axial direction but on the other has to ensure stable axial seating, the more so since there is a not inconsiderable axial thrust in the axial direction of through-flow as a result of the expansions of hot gas within the turbine stages, and this thrust has to be countered.
Conventionally, the unexpected vibration, which cannot be precisely calculated, when gas turbine systems are started up will be countered by measures which are complex from the point of view of engineering construction, by providing additional structural elements which are capable of reducing the vibration behavior of the gas turbine system, in particular when the operational speed of rotation is reached, both on rotary components of the rotor unit and on the stationary gas turbine housing. Making a theoretically precise predictive calculation of disruptive structural resonance of this kind is on the one hand very complex and yet on the other cannot be performed with a satisfactory degree of precision, the more so since once a gas turbine system has been installed broad variations in the frequency at which the respective structural resonance appears will occur. Thus, it is perfectly possible for disruptive structural resonance to occur below or above the respective operational speeds of rotation, in some cases even with gas turbine systems of the same construction. Not least for economic reasons, it is essential to keep the vibration which occurs in operation with gas turbine systems within acceptable limits, the more so since excessive vibration will put the operational reliability of the entire gas turbine system in doubt and ultimately result in a costly decommissioning of the entire gas turbine system.